The cast is based on castaways that were portrayed as overdogs or underdogs in 'a season' they played on Survivor. Note: I find it hard filling the spots in male:underdogs so you guys can fill them

Overdogs Male: Jason or Scott(Koah Rhong), Pete(Philippines), Ian(Palau), Brian Heidik(Thailand), Cochran(SP)

Overdogs Female: Kim Spradlin(One world), Natalie A.(SJDS), Crystal(Gabon), Jenna Morasca(Amazon), Figgy or Michelle(MvGx)

vs

Underdogs Male: Hayden(BvW), Mike H.(WA), Fabio(Nicaragua), David(MvGx), ____________

Uderdogs Female: Alecia(Kaoh Rhong), Christina(One World), Kelley(SJDS), Stephanie(Palau), Francesca(any season lol)

also would consider: Shi-ann or Denise for underdogs and Parvati or Cydney for overdogs

Last of all I wanna be clear with the definition of Overdog/underdogs. Overdogs, for me, are mostly in the majority alliance, were challenge beasts or have a dominant personality (can also be a bully) while underdogs are the opposite.